Bar Stool under bench mounts

We have a couple of robot vacuum cleaners, so my wife always puts the bar stools up on the kitchen bench to allow them to clean under there.
I first tried installing some brackets under the bench to hang the stools slightly off the floor. However, you hit them with you knees when sitting at the bench. So In decided to make the brackets swing up out of the way when not in use. These work well.

To install them, essentially you have to mount the brackets in the retracted position (as shown in